In an effort to minimize the environmental impact of disposable plastics, many municipalities are establishing curbside recycling programs. The mixed polymer recycle stream generated by such recycling programs contains a significant amount of polyethylene terephthalate (PET), typically present in the form of carbonated soft drink bottles. Such bottles are easily identified and may be selectively sorted from other plastics. However, selective sorting of carbonated soft drink bottles does not necessarily segregate PET from other plastics, since the structure of such bottles typically includes polyolefins (e.g. polypropylene caps and labels, and high density polyethylene base cups). If an attempt is made to include other PET bottles, which come in a variety of shapes and sizes, it is possible that some clear polyvinyl chloride and clear polystyrene bottles, or multilayer bottles, will be included with the PET bottles. PET is also utilized for dual ovenable trays and other containers, which typically contain small amounts of other polymers for property improvement. Thus, the recycling of PET food trays provides another route for including other polymers with recycled PET.
A variety of methods have been proposed for recycling PET, with or without other polymers. On a commercial scale, PET is generally depolymerized to oligomers or PET monomers which are subsequently utilized as a raw material in the preparation of recycled PET resin. Such depolymerization provides a route for separating PET from other polymers. However, it would be preferable to avoid the processing costs associated with depolymerizing and then repolymerizing the PET polymer.
It is an object of this invention to recover polyester polymers, particularly PET, from a mixed polymer recycle stream through use of a solvent that selectively dissolves the polyester polymer while maintaining the polyester polymer as a polymer, and substantially rejects dissolution of other polymers present in the mixed polymer recycle stream.